When you enter your search term in Google search box and clicking on “I’m Feeling Lucky” button will automatically take you straight to the top-ranking result returned for your query.
“I’m Feeling Lucky” means you will be get to see the first web page returned for your query without other choices.
What you might not know is that the “I’m feeling lucky” button costs Google $110 million per year, because around 1% of all Google searches go through the “I’m Feeling Lucky” button, Google dosen’t show search ads those searches which goes through “I’m Feeling Lucky”.